1. Field of the Invention
The present invention relates to an image forming system.
2. Description of the Related Art
In the production-oriented printer market, printed materials themselves serve as the products. Hence, emphasis is on the productivity capability of image forming apparatuses that generate printed materials. Moreover, the image forming apparatuses are increasingly having an enhanced productivity so as to generate printed materials at high speed. Furthermore, since printed materials generated by the image forming apparatuses themselves serve as the products; maintaining the quality of the printed materials is also an important factor.
As a measure for maintaining the quality of printed materials, an image inspection device has been developed that inspects whether or not defects such as abnormal images are present in a printed material generated by an image forming apparatus. The image inspection device reads images from the printed material that is generated by an image forming apparatus, compares the image data that is obtained by reading images with the original image data that was used in generating the printed material, and determines whether or not there are any defects in the images formed on the printed material (i.e., performs a defect determination process).
As described above, when printed materials themselves serve as the products, it becomes necessary to ensure that any defective printed material, which has a defective image printed thereon, does not get mixed with normal printed materials having a non-defective image printed thereon. Therein, in the image inspection device, a typically-known technology is implemented to make sure that a defective printed material is discharged to a different discharge destination than the discharge destination for discharging normal printed materials.
There, in an image inspection device that is connected to a device which includes a separate discharge destination for defective printed materials, the defect determination process for determining whether or not there are any defects in the images formed on a printed material needs to be completed before that printed material reaches the device which includes a separate discharge destination for defective printed materials. However, depending on the image data or depending on the inspection details, it takes time to perform the defect determination process. Thus, there are times when the defect determination process does not get completed before a printed material reaches the device which includes a separate discharge destination for defective printed materials. The measures to tackle this issue are being studied.
As a proposed measure to tackle the case in which the defect determination process does not get completed before a printed material reaches the device which includes a separate discharge destination for defective printed materials, a technology has been proposed with the aim of securing sufficient time to ensure completion of the defect determination process. According to that technology, after the images formed on a printed material have been read, the printed material is conveyed forward at a lower conveying speed.
For example, an image forming apparatus has been disclosed that includes an image inspection device having a unit for determining whether or not there are defects in the images formed on a printed material, a discharge destination switching unit for switching between a discharge destination for defective printed materials and a discharge destination for normal printed materials, and a conveying speed control unit being capable of controlling the conveying speed of the printed material. In the image forming apparatus, during a period starting from the reading of the images formed on the printed material until the determination of defects in images is completed, the printed material is conveyed at a lower conveying speed than the specified conveying speed. Hence, it is ensured that a defective printed material is discharged to the discharge destination for defective printed materials, and the productivity is prevented from declining (see Japanese Patent Application Laid-open No. 2010-041430).
Apart from that, for example, an image inspection device has been disclosed that includes a reading unit that reads images; a discharge destination switching unit that switches the discharge destination for printed materials; a printed material storing unit that temporarily stores a printed material and that is disposed in between the reading unit and the discharge destination switching unit; and an image information storing unit that temporarily stores the read image data before the defect determination process is performed. With that, the defect determination process is performed in an asynchronous manner with respect to the conveying of the printed material. That makes it possible to perform the defect determination process having a high degree of freedom in terms of time. As a result, it becomes possible to invest an arbitrary amount of time for inspecting images without hindering the continuous operation of image formation (see Japanese Patent Application Laid-open No. 2009-230046).
However, in the technology disclosed in Japanese Patent Application Laid-open No. 2010-041430, the only countermeasure is to reduce the conveying speed of the printed material to be inspected. Consequently, the productivity of printed materials also decreases. That is, the specified productivity cannot be maintained. Moreover, in the technology disclosed in Japanese Patent Application Laid-open No. 2009-230046, the printed material to be inspected is temporarily stored in the printed material storing unit. Consequently, the specified productivity cannot be maintained as is the case for the technology disclosed in Japanese Patent Application Laid-open No. 2010-041430.
Therefore, there is a need for an image forming system capable of accurately separating a discharge destination for normal printed materials from a discharge destination for defective printed materials while maintaining the productivity of printed materials.